The present invention relates to an effector and to a tool, and particularly, but not exclusively to a surgical tool and an effector therefor.
A known form of surgical tool has an effector mounted at the end of a shaft. The effector has two jaws and is actuated by an actuating member in the shaft. The jaws are pivotally attached to one another scissor fashion by means of a pin joint. The pivotal end of each jaw is attached to a respective ink by a further pin joint. The links attached to the jaws are attached to one another and to the actuating member in the shaft by means of a still further pin joint. Translational movement of the actuating member in the shaft causes the links to move in a scissor-like manner so that the jaws open and close. When the jaws are closed, the jaws, links and actuating member are aligned, axially of the shaft. However, when the jaws are fully open the links and the pivotal ends of the jaws project laterally beyond the diameter of the shaft.
This lateral projection of the links and jaws beyond the diameter of the shaft is undesirable since the tissue of the patient may be caught in the links and jaws of the tool. Furthermore, the pins of the pin joints are very small, so that it is difficult to install the pins securely. The small size of the pins also means that they are very prone to fracture. Again, such fractures are obviously undesirable since they result in the introduction of foreign material into the patient. The mechanical advantage of the tool also varies according to the position of the jaws. As the jaws approach the closed position, the mechanical advantage of the system is greatly reduced in comparison with the mechanical advantage when the jaws are in the fully open position.
An object of the present invention is to provide a tool in which the above disadvantages are overcome.
The invention provides an effector as claimed in claim 1 and a tool as claimed in claim 17.
An embodiment of the invention will now be described with reference to the drawings, in which: